Numerical investigation of the hydrodynamic amplification and thermal instabilities by imposing pulsation during forced convection of air cooling of nine identical heated blocks mounted on a horizontal channel is presented. The finite volume method has been used to solve the governing equations. The feature of this work is a narrowband of frequencies, where the enhancement of heat transfer of all electronic components is in the range of 25%-55% compared with steady nonpulsation flow is obtained. Good agreement between numerical simulations and experimental results available from the literature is obtained.

Forced convection flow of air through power supply box with piezoelectric fan of nine identical electrical devices has been numerically investigated. This work simulates a practical situation in which periodic temperature is generated in an electrical device as a result of its periodic input voltage. The finite volume method has been adopted to solve the governing equations. The effects of important parameters such as pulsation flow frequencies and temperature modulation frequency on heat transfer rates were investigated in details for Re = 500 corresponding to velocity of 0.39 m/s. The piezoelectric vibration amplitude is fixed at 0.2 and frequencies are varied in the range of [0–3] corresponding to [0–287] Hz. We have found that the time averaged Nusselt number for each electrical device depends on the pulsation frequency and heat modulation, and it is always larger than that in the steady‐state case. The results show that there exists a short band of frequencies which the enhancement of heat transfer of all electrical devices is higher than 55% compared with that of steady state. In addition, the heat transfer is maximum when heated pulsation frequency in the device is set as St = 3.0 corresponding to frequency of 58.5 Hz of input voltage. The combined pulsation flow by piezoelectric fan and heated pulsation by input voltage show vigorous heat transfer through electrical devices blocks and the heat transfer enhancement was observed in relatively narrow bands of frequencies. The efficiency of piezoelectric fan is expressed by the maximum temperature of the ninth electrical device which not exceed 80°C for time‐averaged velocity of 0.556 m/s and vibration frequency of 34.75 Hz of piezoelectric fan. The pressure drop and power pumping of piezoelectric fan are obtained for different Reynolds numbers. We found that the power loss was 4.6 times higher than for the piezoelectric fan at Re = 500. Good agreement between our numerical simulations of piezoelectric fan and experimental results available from the literature is obtained. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Many extensive studies have shown that thermal comfort in inhabited buildings has a strong influence on the quality of life of the occupants. At the same time, it is well known that poor thermal comfort can cause adverse physiological effects.This is the case in Algeria, where collective residential buildings have low thermal performance. According to this fact, most of the inhabitants of these buildings suffer from a great lack of thermal comfort. Similarly, the measurements taken of the state of the insulation of these buildings cannot exclude that a problem related to the thermogenic quality exists and needs to be corrected urgently. In this sense that the objective of this study aims to determine the level of deterioration of thermal comfort by demonstrating the unbearable periods of the year, which create a discomfort among the inhabitants of the collective residential buildings of the Bouzaaroura estate in Annaba. At first, a sociological investigation was established near the inhabitants of this housing estate in order to evaluate their feelings towards the quality of the thermal wellbeing of their housing. Second, a numerical simulation of one of the modelled buildings was carried out using the Design Builder software. The result of the comparative analysis between the results of the survey and the simulation revealed that 91.7% of the inhabitants felt very uncomfortable with the thermal discomfort in their homes, with a Predicted Mean Vote (PMV) indicator of -2.6, a Predicted Percentage Dissatisfied (PPD) indicator of 94%, and that only 44% suffered from heat in the summer, while all of them felt cold in the winter.

The study in question consists to amplify the hydrodynamic and thermal instabilities by imposed pulsation during forced convection of air cooling of nine identical heated blocks simulate electronic components mounted on horizontal channel. The finite volume method has been used to solve the governing equations of unsteady forced convection. This approach uses control volume for velocities that are staggered with respect to those for temperature and pressure. The numerical procedure called SIMPLER is used to handle the pressure-velocity coupling. The results show that the time averaged Nusselt number for each heated block depends on the pulsation frequencies and is always larger than in the steady-state case. The new feature in this work is that we obtained a short band of frequencies which the enhancement of heat transfer of all electronic components is greater than 20 % compared with steady non pulsation flow. In addition, the gain in heat transfer Emax attainted the maximum value for the central blocks. Our numerical results were compared with other investigations and found to agree well with experimental data.